Various utilities such as Water supply and Sewerage Board, Gas Utilities, Municipal Authorities etc. bury pipe to connect with mains below the surface of the earth. Depending on the type of the utility, the installation and location of the pipes can vary. For example, in the case of water supply utilities, pipes are installed from source to storage to water treatment plant to main reservoir, to houses and communities being serviced. In the case of gas utilities, pipes carry gas from a production facility to a processing facility to gate stations to homes and businesses. The materials used in making pipes for a utility can vary based on functional specifications and includes, among others well known to persons of ordinary skill in the art, fiberglass piping, plastic piping, metal piping or concrete piping.
Different detection and location methods exist to locate the pipes that are underground. For example, the location of a metal pipe is easily determined by means of magnetometer devices or by applying RF signals to the pipe and picking up the radiation from the pipe with a sensing device. For pipes that avoid detection by magnetometer or RF signal such as plastic pipes, there is no suitable conventional location technique. For example, it is common practice to provide markings on curbings and to use ‘as-built’ drawings for reference to locate underground pipes. However, experience shows that these markings and drawings are not always accurate and often many holes must be dug in an attempt to locate the pipe. With the large number of plastic pipes installations, the randomness of the dig and locate method is impractical.
Sometimes locating wires are laid alongside, spiraled around, or taped to the plastic pipes. U.S. Pat. Nos. 4,573,829, 6,286,542, and 5,044,824 describe methods and means to insert a conducting wire into an existing pipeline so as to detect the location of pipe. However, while these locating wires are more accurate than the dig and locate method, they also pose problems as they can easily be dislodged or knocked off from the pipe during transit from the manufacturing point or during installation of the pipe, and no longer follow the path of the plastic pipes. As such known methods of using locating wires do not present a sustainable and effective solution for traceability.
Additionally, not only is it important to be able to determine the exact location of pipes, it also important to be able to determine if a pipe is damaged or if there is a leak in a pipeline. Various known methods are available for the detection of leaks in pipes. In one such system, an electric pulse is sent down a transmission line placed in proximity to a pipe being monitored. Reflections of the pulses are monitored and threshold values are established above and below the reflected waveforms. Upon the occurrence of a leak or break in the pipe or a break in the cable, the characteristic impedance of the line changes thus resulting in a change in the waveform of the reflection. If the change in impedance is sufficient to cause the waveform to cross either the upper or lower threshold, a leak or break is indicated. By noting the position of the change in shape of the waveforms, the location and other characteristics of the leak may be determined. However, this method requires the use of transmission line, which may cause an irregularity in impedance when the transmission wire becomes dislodged or damaged from the pipe even though the pipe is not itself damaged. When only the transmission line is damaged (but not the pipe) unnecessary time, materials and expenses are spent to repair or fix a duct body with no actual damage. The result is that the transmission wire becomes an ineffective tool for determining if an actual repair is needed because it is not certain if the irregularity in impedance is caused by the damaged duct body or a damaged transmission wire.
Thus, to overcome the aforementioned drawbacks, there exists a need for a simple, economical and practical system that can locate the pipe, detect leakage, or both in a non-metallic pipe using a tracer wire that is not easily dislodged or broken when coupled to a duct body.